The world’s astronomers passionately debated a plan to use roundness as the criterion for defining a ‘planet, with some experts calling the proposal ‘reasonable’ but others declaring that it is ‘bound to fail’.
Pluto would qualify as a “dwarf planet” distinct from the solar system’s eight “classical planets” under the definition presented by a panel at the International Astronomical Union (IAU) conference here on Tuesday.
Yet the special panel also recommended the eight bodies from Mercury to Neptune share the general term ‘planet’ with Pluto and other ‘trans-Neptunian objects’ because they orbit a star and meet gravitational criteria for “hydrostatic equilibrium”, which makes them “nearly round”.
Moreover, the panel suggested calling Pluto and its space companion Charon a ‘double planet’. In a non-binding show of hands after a 90-minute debate, International Astronomical Union members voted “about 50-50” in favour of the proposal’s main resolution, said IAU spokesman Lars Christensen. But “a clear majority” opposed two other resolutions.